This paper presents results from three interrelated studies focusing on introducing TRAKLA2 to students taking courses on data structures and algorithms at the University of Turku and \rAbo Akademi University in 2004. Using TRAKLA2 they got acquainted with a completely new system for solving exercises that provided them with automatic feedback and the possibility to resubmit their solutions. Besides comparing the students' learning results, a survey was made with 100 students on the changes in their attitudes towards web-based learning environments. In addition, a usability evaluation was conducted in a human-computer interaction laboratory. Our results show that TRAKLA2 considerably increased the positive attitudes towards web-based learning. According to students' self-evaluations, the best learning results are achieved by combining traditional exercises with web-based ones. In addition, the numerical course statistics were clearly better than in 2003 when only pen-and-paper exercises in class were used. The results from the usability test were also very positive: no severe usability problems were revealed; in fact, the results indicate that the system is very easy to learn and user-friendly as a whole.